1. Field of the Invention
The present invention relates to a semiconductor wafer cleaning apparatus.
2. Description of the Related Art
Generally, with the high integration of semiconductor memory devices, micro-particles contained on the wafer surface exert a great influence on the characteristics of the semiconductor memory devices. Thus, recently, techniques for removing micro-particles contained on a wafer surface have become increasingly important in fabricating a semiconductor memory device.
Also, since the fabrication of a large wafer is currently under way, a large cleaning tank is necessary, and thus, the overall wafer cleaning apparatus occupies a large space. Therefore, conventionally, methods for diminishing the size of the cleaning tank have been proposed in order to prevent the volume increase of the wafer cleaning apparatus. However, if the volume of the wafer cleaning apparatus is reduced, the spacing between wafers becomes narrower, which decreases the homogeneity of reaction between the cleansing solution and each wafer and reduces the reaction effect, thereby disabling the overall wafers to be cleaned uniformly.
On the other hand, conventionally proposed wafer cleaning apparatuses have been adopting a Laminar flow method and a stirring method. Such conventional semiconductor wafer cleaning apparatuses will be described with reference to FIGS. 1 and 2.
FIG. 1 is a schematic diagram of a conventional semiconductor wafer cleaning apparatus adopting a Laminar flow method in which a wafer is carried within a cassette and is dipped into a cleansing solution to be cleaned.
As shown, the semiconductor wafer cleaning apparatus includes a wafer cleaning internal tank 21, a cassette 23 positioned within the internal tank 21 and having a wafer 25 carried therein, an outer tank 27 installed on the outer side of the internal tank 21 and having a cleansing solution outlet 28 formed through the sidewall thereof, a circulating pump 33 connected with a cleansing solution inlet 29 formed in the internal tank 21 for circulating the cleansing solution, and a filter 35 for filtering the circulated cleansing solution.
In the cleaning apparatus having the aforementioned configuration, first, the cleansing solution passes through the filter 35 by the operation of the circulating pump 33 and fills the internal tank via the cleansing solution inlet 29. Thereafter, wafers 25 supported in the cassette 23 are dipped into the cleansing solution. At this time, the particles contained on the surface of the wafers 25 react with the cleansing solution to clean the wafers 25.
However, in the case of such apparatus, since the wafers dipped into the cleansing solution are only cleaned, the time for cleaning the wafers grows longer, thereby prolonging the fabrication processing time of overall semiconductor memory devices. Also, the cleansing efficiency is decreased to then deteriorate the cleaning uniformity on the whole surface of the wafers.
Another conventional semiconductor wafer cleaning apparatus is a stirring wafer cleaning apparatus using an ultrasonic generator, as shown in FIG. 2. As shown, an ultrasonic generator 43 is installed in a lower cleaning tank 41 and an inlet 45 is formed in the sidewall thereof for inducing pure water. A supporting plate 47 is installed within the cleaning tank 41, a wafer carrier 49 is installed on the supporting plate 47, and a plurality of wafers 51 are carried within the wafer carrier 49 with a predetermined spacing therebetween.
Also, a plurality of water holes 53 are formed on the supporting plate 47 so that the pure water passes toward the upper supporting plate 47 while being stirred by the ultrasonic generator 43. The pure water is turbulently stirred by the ultrasonic vibration generated by the ultrasonic generator 43 in the state where the cleaning tank 41 is filled with water.
Subsequently, impure particles stuck on the surface of wafers 51 collide with the stirred water and are thereby detached from the surface of the wafers 51, thereby allowing the cleaning of the wafers 51.
In the case of the wafer cleaning apparatus of FIG. 2, the cleaning process of the wafers 51 dipped in the cleaning tank 41 is similar to that performed by the Laminar flow method shown in FIG. 1. Since the apparatus of FIG. 2 is used for cleaning wafers by stirring pure water using the ultrasonic generator 43, it is more effective in cleaning wafers than the wafer cleaning apparatus adopting the above-described Laminar flow method. However, since a constant period of time should elapse in order to stir the water in the cleaning tank 41, the time for cleaning wafers is prolonged.
As described above, the conventional semiconductor wafer cleaning apparatus involves the following problems. First, when the wafer size is increased, the size of the cleaning tank should be increased accordingly. Thus, the overall wafer cleaning apparatus becomes larger. Second, if the pitch between wafers is made narrow for preventing the volume of the cleaning apparatus from being increased, the chemical reaction between the cleansing solution and wafers is retarded, thereby disabling the uniform cleaning of the overall surface of the wafers.
To solve the above problems, it is an object of the present invention to provide a semiconductor wafer cleaning apparatus using a jet nozzle which can reduce the overall wafer cleaning process and increase the wafer cleaning uniformity, by removing impure particles contained on the surface of the wafers using the jet nozzle in a short time.
Additional objects and advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the above objects and in accordance with the purpose of the invention, as embodied and broadly described herein, the semiconductor wafer cleaning apparatus of this invention comprises an outer tank, a cleaning tank installed in the outer tank, a wafer carrier provided within the cleaning tank, a plurality of jet nozzles directed toward the wafer carrier, a main pipe connected with the jet nozzles, a circulating pump connected with the main pipe and the outer tank for circulating a cleansing solution from the outer tank, through the main pipe, the jet nozzles, and the cleaning tank, and back to the outer tank, and a filter for filtering the circulated cleansing solution.